1. Field of the Invention
The present invention relates to a coating treatment method, a non-transitory computer storage medium and a coating treatment apparatus coating a coating solution onto a substrate.
2. Description of the Related Art
In a photolithography process in a manufacturing process of a semiconductor device, for example, a resist coating treatment of coating a resist solution onto a semiconductor wafer (hereinafter, referred to as a “wafer”) to form a resist film, exposure processing of exposing the resist film to a predetermined pattern, a developing treatment of developing the exposed resist film and so on are performed in sequence to form a predetermined resist pattern on the wafer.
In the above-described resist coating treatment, a so-called spin coating method is frequently used in which a resist solution is supplied from a nozzle to a central portion of the rotating wafer and a centrifugal force is utilized to diffuse the resist solution over the wafer to thereby coat the resist solution on the wafer. It is necessary to coat the resist solution on the wafer with high in-plane uniformity when the resist coating as stated above is performed. Besides, it is also important in this spin coating method to reduce a supply amount of the resist solution on the wafer because a most part of the resist solution supplied on the wafer is spun off and the resist solution is expensive.
A coating treatment method executing a first step to a third step stated below is proposed as a method of uniformly coating the resist solution with a small amount in the spin coating method as stated above. At first, in the first step, the resist solution is supplied to the central portion of the wafer rotating at high speed at a first rotation number to diffuse the resist solution on the wafer. In this first step, the amount of the resist solution supplied on the wafer is small, and therefore the resist solution does not diffuse to an end of the wafer. Subsequently, in the second step, the number of rotations of the wafer is once decelerated to a second rotation number, and the supply of the resist solution in the first step is continued so as to improve fluidity of the resist solution on the wafer. After that, in the third step, the rotation of the wafer is accelerated to a third rotation number to diffuse the resist solution to a whole surface of the wafer, and perform drying of the diffused resist solution, and the resist solution with a uniform film thickness is coated on the wafer, after the supply of the resist solution in the second step is stopped (Japanese Patent Application Laid-open No. 2008-71960).